NEW YORK :An index of global stocks edged higher in choppy trading on Thursday as markets digested lackluster revenue forecasts from artificial-intelligence chipmaker Nvidia, while oil prices climbed amid rising tension from the Russia-Ukraine war. Shares of Nvidia, the world's most valuable company and a major contributor to the gains this year in the benchmark S&P 500, hit a record high early in the session before reversing direction and declining about 1 per cent. The chipmaker forecast its